module main

import os
import gg
import gx
import rand
import sokol.sgl

const (
    win_width     = 800
    win_height    = 600
    max_stars     = 5000
    max_v_letters = 5
)

struct Star {
mut:
    x f32
    y f32
    z f32
    r f32
    g f32
    b f32
}

struct VLetter {
mut:
    x      f32
    y      f32
    z      f32
    w      f32
    h      f32
    angle  f32
    dz     f32
    dangle f32
}

struct App {
mut:
    gg        &gg.Context = unsafe { nil }
    image     gg.Image
    stars     []Star
    v_letters []VLetter
}

fn main() {
    mut app := &App{
        gg: 0
        stars: []Star{len: max_stars}
        v_letters: []VLetter{len: max_v_letters}
    }
    app.gg = gg.new_context(
        bg_color: gx.black
        width: win_width
        height: win_height
        create_window: true
        window_title: 'Star Vield'
        frame_fn: frame
        init_fn: init_images
        user_data: app
    )
    for i in 0 .. max_stars {
        app.stars[i].x = rand.f32_in_range(-200.0, 200.0) or { -200.0 }
        app.stars[i].y = rand.f32_in_range(-200.0, 200.0) or { -200.0 }
        app.stars[i].z = rand.f32_in_range(-200.0, -100.0) or { -200.0 }
        app.stars[i].r = rand.f32_in_range(0.1, 1.0) or { 0.1 }
        app.stars[i].g = rand.f32_in_range(0.1, 1.0) or { 0.1 }
        app.stars[i].b = rand.f32_in_range(0.1, 1.0) or { 0.1 }
    }
    for i in 0 .. max_v_letters {
        app.v_letters[i].x = rand.f32_in_range(-20.0, 20.0) or { -20.0 }
        app.v_letters[i].y = rand.f32_in_range(-20.0, 20.0) or { -20.0 }
        app.v_letters[i].z = rand.f32_in_range(-5.0, -1.0) or { -5.0 }
        app.v_letters[i].w = rand.f32_in_range(5, 20) or { 5 }
        app.v_letters[i].h = app.v_letters[i].w
        app.v_letters[i].angle = rand.f32_in_range(0, 6.283184) or { 0 }
        app.v_letters[i].dangle = rand.f32_in_range(-0.05, 0.05) or { -0.05 }
        app.v_letters[i].dz = rand.f32_in_range(-0.1, -0.01) or { -0.1 }
    }
    app.gg.run()
}

fn init_images(mut app App) {
    mut logo_path := os.resource_abs_path(os.join_path('..', 'assets', 'logo.png'))
    app.image = app.gg.create_image(logo_path) or { panic(err) }
}

fn frame(mut app App) {
    app.gg.begin()
    app.draw()
    app.gg.end()
}

// fn C.glPointSize(size f32)
fn (mut app App) draw() {
    sgl.defaults()
    sgl.perspective(sgl.rad(90), 1.0, 1.0, 100.0)
    // C.glPointSize(3.0)
    sgl.begin_points()
    for i in 0 .. app.stars.len {
        s := app.stars[i]
        sgl.v3f_c3f(s.x, s.y, s.z, s.r, s.g, s.b)
        app.stars[i].z += 0.3
        if app.stars[i].z > -1.0 {
            app.stars[i].x = rand.f32_in_range(-200.0, 200.0) or { -200.0 }
            app.stars[i].y = rand.f32_in_range(-200.0, 200.0) or { -200.0 }
            app.stars[i].z = rand.f32_in_range(-200.0, -100.0) or { -200.0 }
        }
    }
    sgl.end()
    // ////
    for i in 0 .. app.v_letters.len {
        v := app.v_letters[i]
        sgl.defaults()
        sgl.perspective(sgl.rad(90), 1.0, 1.0, 100.0)
        sgl.rotate(v.angle, 0, 0, 1)
        app.gg.draw_image_3d(v.x, v.y, v.z, v.w, v.h, app.image)
        //
        app.v_letters[i].z += app.v_letters[i].dz
        app.v_letters[i].angle += app.v_letters[i].dangle
        if app.v_letters[i].z > -60.0 {
            app.v_letters[i].x += rand.f32_in_range(-0.05, 0.05) or { -0.05 }
            app.v_letters[i].y += rand.f32_in_range(-0.05, 0.05) or { -0.05 }
        }
        if app.v_letters[i].z < -95.0 {
            app.v_letters[i].h *= 0.8
            app.v_letters[i].w *= 0.8
        }
        if app.v_letters[i].z < -100.0 {
            app.v_letters[i].z = rand.f32_in_range(-5.0, -1.0) or { -5.0 }
            app.v_letters[i].h = 10.0
            app.v_letters[i].w = 10.0
        }
    }
}